ELECTRO CHEMISTRY
● Oxidation: It is defined as a loss of electrons while reduction is defined
as a gain of electrons.
In a redox reaction, both oxidation and reduction reaction takes place
simultaneously.
● Direct redox reaction: In a direct redox reaction, both oxidation and
reduction reactions take place in the same vessel. Chemical energy is
converted to heat energy in a direct redox reaction.
● Indirect redox reaction: In indirect redox reactions, oxidation and
reduction take place in different vessels.
In an indirect redox reaction, chemical energy is converted into electrical
energy. The device which converts chemical energy into electrical energy
is known as an electrochemical cell.
● In an electrochemical cell:
● The half-cell in which oxidation takes place is known as
oxidation half-cell
● The half-cell in which reduction takes place is known as
reduction half-cell.
● Oxidation takes place at anode which is negatively charged
and reduction takes place at cathode which is positively
charged.
● Transfer of electrons takes place from anode to cathode while
electric current flows in the opposite direction.
● An electrode is made by dipping the metal plate into the
electrolytic solution of its soluble salt.
● A salt bridge is a U shaped tube containing an inert
electrolyte in agar-agar and gelatine.
, ● Salt bridge: A salt bridge maintains electrical neutrality and allows the
flow of electric current by completing the electrical circuit.
● Representation of an electrochemical cell:
● Anode is written on the left while the cathode is written on
the right.
● Anode represents the oxidation half-cell and is written as:
Metal/Metal ion (Concentration)
● Cathode represents the reduction half-cell and is written as:
Metal ion (Concentration)/Metal
● Salt bridge is indicated by placing double vertical lines
between the anode and the cathode
● Electrode potential is the potential difference that develops
between the electrode and its electrolyte. The separation of
charges at the equilibrium state results in the potential
difference between the metal and the solution of its ions. It is
the measure of tendency of an electrode in the half cell to lose
or gain electrons.
● Standard electrode potential: When the concentration of all
the species involved in a half cell is unity, then the electrode
potential is known as standard electrode potential. It is
denoted as EΘ.
● According to the present convention, standard reduction potentials are
now called standard electrode potential.
● Types of electrode potential: There are 2 types of electrode potentials
namely,
● Oxidation potential
● Reduction potential
● Oxidation potential: It is the tendency of an electrode to lose electrons or
get oxidized.
● Reduction potential: It is the tendency of an electrode to gain electrons
or get reduced.
Oxidation potential is the reverse of reduction potential.
● The electrode having a higher reduction potential have higher tendency to
gain electrons and so it acts as a cathode whereas the electrode having a
lower reduction potential acts as an anode.
● Oxidation: It is defined as a loss of electrons while reduction is defined
as a gain of electrons.
In a redox reaction, both oxidation and reduction reaction takes place
simultaneously.
● Direct redox reaction: In a direct redox reaction, both oxidation and
reduction reactions take place in the same vessel. Chemical energy is
converted to heat energy in a direct redox reaction.
● Indirect redox reaction: In indirect redox reactions, oxidation and
reduction take place in different vessels.
In an indirect redox reaction, chemical energy is converted into electrical
energy. The device which converts chemical energy into electrical energy
is known as an electrochemical cell.
● In an electrochemical cell:
● The half-cell in which oxidation takes place is known as
oxidation half-cell
● The half-cell in which reduction takes place is known as
reduction half-cell.
● Oxidation takes place at anode which is negatively charged
and reduction takes place at cathode which is positively
charged.
● Transfer of electrons takes place from anode to cathode while
electric current flows in the opposite direction.
● An electrode is made by dipping the metal plate into the
electrolytic solution of its soluble salt.
● A salt bridge is a U shaped tube containing an inert
electrolyte in agar-agar and gelatine.
, ● Salt bridge: A salt bridge maintains electrical neutrality and allows the
flow of electric current by completing the electrical circuit.
● Representation of an electrochemical cell:
● Anode is written on the left while the cathode is written on
the right.
● Anode represents the oxidation half-cell and is written as:
Metal/Metal ion (Concentration)
● Cathode represents the reduction half-cell and is written as:
Metal ion (Concentration)/Metal
● Salt bridge is indicated by placing double vertical lines
between the anode and the cathode
● Electrode potential is the potential difference that develops
between the electrode and its electrolyte. The separation of
charges at the equilibrium state results in the potential
difference between the metal and the solution of its ions. It is
the measure of tendency of an electrode in the half cell to lose
or gain electrons.
● Standard electrode potential: When the concentration of all
the species involved in a half cell is unity, then the electrode
potential is known as standard electrode potential. It is
denoted as EΘ.
● According to the present convention, standard reduction potentials are
now called standard electrode potential.
● Types of electrode potential: There are 2 types of electrode potentials
namely,
● Oxidation potential
● Reduction potential
● Oxidation potential: It is the tendency of an electrode to lose electrons or
get oxidized.
● Reduction potential: It is the tendency of an electrode to gain electrons
or get reduced.
Oxidation potential is the reverse of reduction potential.
● The electrode having a higher reduction potential have higher tendency to
gain electrons and so it acts as a cathode whereas the electrode having a
lower reduction potential acts as an anode.
